The present invention relates generally to equipment employed in the performance of perfusion catheterization procedures, and more particularly, to manually powered pumping apparatus which interconnects an aspiration catheter with a percutaneous transluminal coronary angioplasty (PTCA) catheter or the like to provide a constant, preselected flow of body fluids through the catheter.
Inflatable balloon catheters are commonly used in the treatment of coronary conditions by expanding blockages in arteries. These blockages constitute a narrowing of an artery and are referred to as a stenoses. In coronary procedures, and particularly in PTCA procedures, a guide catheter is inserted into a patient's artery and guided therethrough until the catheter distal tip is positioned in the artery near the stenosis. A dilation catheter which has an inflatable balloon affixed to its distal end is introduced along the guide catheter and advanced along the guide catheter until the balloon end is located at the stenosis. The balloon is then inflated to expand it against the artery and thereby compress the stenosis. This balloon expansion may remove all or most of the blockage.
Once the artery has been expanded, the balloon is deflated. The balloon and guide catheter are subsequently removed and blood again flows through the artery. Often, after expansion and removal of the balloon, the arterial wall may contract and assume part of or its original, restricted state. This contraction is referred to as restenosis. Restenosis is believed to be avoided if the balloon is inflated for longer inflation times. Ischemia, which is a local deficiency of oxygen caused by an obstruction in a blood vessels, may occur with longer balloon inflation times.
Perfusion catheters are used in association with coronary angioplasty, or balloon, catheters to avoid ischemia. Perfusion catheters are catheters which permit the continuous flow of blood through the blockage during the inflation of the balloon in the artery. Perfusion of blood through a balloon catheter is accomplished by providing a balloon having one or more passages, or lumens, which serve as passages extending through the balloon. These passages permit blood to flow through the blockage and through the balloon. In perfusion, a reliable pump is needed to pump blood continuously through the balloon passages. A specific flow rate through perfusion catheters, such as 60 cc per minute is desirable to avoid ischemia. Perfusion catheter lumens possess minute diameters which are approximately three mils (0.003 inch). External pumps used for perfusion must provide a continuous flowrate of blood at high pressures approaching 300 psi or so to continuously pump blood at flowrates of 60 cc per minute or so. External pumps are needed in order to maintain these high pumping pressures and therefore pump blood through small lumens of these catheters through the balloon inflation area, rather than rely upon the patient's heart to pump the blood. These external pumps preferably would draw blood from the patient by way of an aspiration catheter and circulate it back into the patient through the perfusion catheter past the distal end of the balloon.
External blood pumps are well-known and have been commonly used for regulating blood through coronary arteries during open-heart surgeries, but necessarily for perfusion procedures. Open-heart pumps may include a roller type pumping apparatus and generally have a low pressure output and, thus may not be able to supply a high pressure necessary to pump blood at a flowrate of 60 cc per minute through perfusion catheter lumens. Positive displacement pumps which use conventionally powered pistons may create pressure pulses during pumping which may result in pressure transients during pumping. Single-stroke pumps at best may only provide intermittent blood flow because every pumping stroke of the pump requires a suction stroke to refill the pump piston.
A need therefore exists for reliable perfusion pump for use in PCTA and other catheterization procedures which continuously and simultaneously pumps and withdraws blood from and into a patient through small diameter catheter lumens. It would be further desirable if such perfusion pumps utilized disposable components, such as syringes, as their pumping members, to avoid repeated sterilization of the pump.
Some external syringe pumps are described in the art, such as the one described in U.S. Pat. No. 3,447,479, issued Jun. 2, 1967. This patent describes a multiple syringe pump arrangement which performs alternating suction and pumping strokes. In this multiple syringe pump arrangement, four syringe pumps are spaced--apart on a base and their plunger located in the center of the base in contact with a motor-driven eccentric cam. Return springs must be used on these pump plungers to ensure the prompt return of the plungers to their original positions within the syringes. This mechanism is unduly complicated and the possibility exists that the springs and cam may not always reliably power the pumps through a complete suction and pumping cycle because of wear.
The present invention is directed to a manually operated external pumping apparatus for use in catheterization, and particularly perfusion catheterization which continuously and reliably both withdraws blood from a patient and reintroduces the blood back into the patient by simultaneously performing a pumping stroke in one syringe and a suction stroke in another syringe.
In accordance with one aspect of the present invention, a housing member is provided which supports two positive displacement pumps, each of the pumps having a plunger slidable within a pump chamber, the plunger of one pump being affixed to a driving rack member and the plunger of another pump being affixed to a driven rack member. Both rack members are engaged by a pinion gear and the driving rack member further engages a pump handle. When the handle is rotated, the driving rack moves linearly back and forth to impart first a pumping action and second a suction action in the pump affixed to the driving rack. The pinion gear rotates in response to the movements of the driving rack member and this rotation induces a reverse linear movement in the driven rack member, such that while the driving rack member and pump affixed thereto performs a suction stroke, the other pump performs a pumping stroke and vice-versa. The pumping apparatus thus provides a continuous flow of blood during its operation.
In another aspect of the present invention, two syringe pumps of the type having a plunger slidable within a barrel portion are supported within two channels of the housing 12. Each channel engages the barrel portion of its associated pump and restrains them from movement relative to the plunger portions. An actuating mechanism reciprocates both plungers of the two pumps in opposite directions such that at any given moment during operation of the apparatus, the actuating mechanism engages the plunger member of one pump in a pumping mode and the plunger member of the other syringe pump in a suction mode. The actuating mechanism includes a rack and pinion assembly linked to a handle driven by the operator. The handle engages a drive gear and rotation thereof is converted to linear reciprocating movement in the driving rack.
Accordingly, it is an object of the present invention to provide an external perfusion pumping apparatus for use in PTCA and other related catheterization procedures which can readily supply a continuous supply of blood or other body fluids at high pumping pressures required for the perfusion of these fluids through catheter minute diameters.
Another object of the present invention is to provide a manually operated pumping apparatus having multiple pump elements supported in a housing, the pumping apparatus including a handle drive assembly operatively engaging the pump elements to simultaneously drive one pumping element in a pumping stroke and another pump element in an aspirating stroke, whereby the pumping apparatus provides a continuous supply of body fluids to a perfusion catheter or other catheter.
Still another object of the present invention is to provide a pumping apparatus for use in perfusion catheterization wherein the pumping apparatus includes two syringe pumps of the type having a plunger component slidable within a barrel component, each of the syringe pumps being supported within a housing such that the barrel components are fixed from movement relative to their plunger components, each of the plunger components engaging an elongated rack member extending longitudinally within the housing, the two pumps being interconnected by way of a pinion gear rotatably mounted in the housing between two rack members and in engagement therewith, the pinion gear driving one of the pumps in a reciprocating manner in response to an opposing, reciprocating movement of the other of the pumps such that at any instant during operation of the pumping apparatus, one of the two syringe pumps is constantly aspirating blood from a blood source and the other of the two syringe pumps is constantly pumping blood from the blood source into the patient to achieve a continuous flow of blood through the apparatus and into the patient at a preselected flowrate to prevent ischemia from occurring in the patient due to a prolonged lack of blood.
Still yet another object of the present invention is to provide an improved pumping apparatus for use in perfusion and other catheterization procedures wherein two syringe pumps are manually powered by a gear-slider mechanism such that each of the two syringe pumps perform alternating pumping and suction strokes, and whereby the gear-slider mechanism returns to each pump to its initial operating position after movement without the necessity for return springs or the like.
These and other objects features an advantages of the present invention will be clearly understood through consideration of the following detailed description.